#include <graphics.h>
#include <stdlib.h>
#include <dos.h>
/*定义控制命令*/
#define LEFT  0x4b00
#define RIGHT 0x4d00
#define DOWN  0x5000
#define UP 	  0x4800
#define ESC   0x011b

/*定义蛇的最大节数*/
#define NODE 200

int i,key;
int score=0;/*得分*/
/*定义游戏速度*/
int SPEED=100;
/*定义食物的结构体*/
struct Food
{
   int x;/*食物的横坐标*/
   int y;/*食物的纵坐标*/
   int need;/*判断是否要出现食物的变量*/
};
/*定义蛇的结构体*/
struct Snake
{
   int x[NODE];
   int y[NODE];
   int node;/*蛇的节数*/
   int direction;/*蛇移动方向*/
   int life;/* 蛇的生命,0活着,1死亡*/
};

struct Food food;
struct Snake snake;
/*开始画面，左上角坐标为（50，40），右下角坐标为（600，450）的围墙*/
void DrawFence(void)
{
   setcolor(WHITE);
   /*画围墙的上边*/
   line(50,40,600,40);
   line(50,42,600,42);
   /*画围墙的下边*/
   line(50,450,600,450);
   line(50,452,600,452);
	 /*画围墙的左边*/
	 line(50,40,50,450);
	 line(52,40,52,450);
	 /*画围墙的右边*/
	 line(600,40,600,450);
	 line(602,40,602,450);
}

/*输出成绩*/
void PrintScore()
{   
   char string[10];
   setfillstyle(SOLID_FILL,YELLOW);
   bar(50,15,220,35);
   setcolor(RED);
   settextstyle(0,0,2);
   sprintf(string,"score:%d",score);
   outtextxy(55,20,string);
}
/*游戏结束*/
void GameOver()
{
   cleardevice(); 
   PrintScore();
   setcolor(RED);
   settextstyle(0,0,4);
   outtextxy(200,200,"GAME OVER");
   getch();
}
/*画蛇函数*/
void DrawSnake()
{
	setcolor(4);
	for(i=0;i<snake.node;i++)
		rectangle(snake.x[i],snake.y[i],snake.x[i]+10,snake.y[i]-10);
  delay(SPEED);
  setcolor(0);
  rectangle(snake.x[snake.node-1],snake.y[snake.node-1],
	snake.x[snake.node-1]+10,snake.y[snake.node-1]-10);
}
/*玩游戏具体过程*/
void PlayGame()
{
   randomize();/*随机数发生器*/
   food.need=1;/*1表示需要出现新食物,0表示已	经存在食物*/
   snake.life=0;/*活着*/
   /*方向往右*/
   snake.direction=1;
   /*蛇头*/
   snake.x[0]=100;
   snake.y[0]=100;
   snake.x[1]=110;
   snake.y[1]=100;
   snake.node=2;/*节数*/
   PrintScore();/*输出得分*/
   while(1)/*可以重复玩游戏,压ESC键结束*/
   {
      while(!kbhit())/*在没有按键的情况下,蛇自己移动身体*/
      {
	 			if(food.need==1)/*需要出现新食物*/
	 			{
	   			food.x=rand()%400+60;
	   			food.y=rand()%350+60;
	   			while(food.x%10!=0)/*食物随机出现后必须让食物能够在整格内,这样才可以让蛇吃到*/
						food.x++;
	   			while(food.y%10!=0)
						food.y++;
		 			food.need=0;/*画面上有食物了*/
	 			}
	 			if(food.need==0)/*画面上有食物了就要显示*/
	 			{
      		setcolor(GREEN);
      		rectangle(food.x,food.y,food.x+10,food.y-10);
	 			}
        for(i=snake.node-1;i>0;i--)/*蛇的每个环节往前移动,也就是贪吃蛇的关键算法*/
        {
          snake.x[i]=snake.x[i-1];
	    		snake.y[i]=snake.y[i-1];
	 			}
       /*1,2,3,4表示右,左,上,下四个方向,通过这个判断来移动蛇头*/
	 			switch(snake.direction)
	 			{
	    		case 1:snake.x[0]+=10;break;
	    		case 2: snake.x[0]-=10;break;
	    		case 3: snake.y[0]-=10;break;
	   			case 4: snake.y[0]+=10;break;
	 			}
	 			for(i=3;i<snake.node;i++)/*从蛇的第四节开始判断是否撞到自己了，因为蛇头为两节，第三节不可能拐过来*/
	 			{
	    		if(snake.x[i]==snake.x[0]&&snake.y[i]==snake.y[0])
	    		{
            GameOver();/*显示失败*/
            snake.life=1;
            break;
	    		}
        }
				if(snake.x[0]<55||snake.x[0]>595||snake.y[0]<55||snake.y[0]>455)/*蛇是否撞到墙壁*/
				{
	    		GameOver();/*本次游戏结束*/
	    		snake.life=1; /*蛇死*/
				}
				if(snake.life==1)/*以上两种判断以后,如果蛇死就跳出内循环，重新开始*/
           break;
				if(snake.x[0]==food.x&&snake.y[0]==food.y)/*吃到食物以后*/
				{
          setcolor(0);/*把画面上的食物东西去掉*/
          rectangle(food.x,food.y,food.x+10,food.y-10);
	   			snake.x[snake.node]=-20;snake.y[snake.node]=-20;
          /*新的一节先放在看不见的位置,下次循环就取前一节的位置*/
	   			snake.node++;/*蛇的身体长一节*/
	   			food.need=1;/*画面上需要出现新的食物*/
	   			score+=10;
	  		  PrintScore();/*输出新得分*/
				}
				DrawSnake();
     	}
    	if(snake.life==1)/*如果蛇死就跳出循环*/
        break;
      key=bioskey(0);/*接收按键*/
    	if(key==ESC)/*按ESC键退出*/
        break;
    	else if(key==UP&&snake.direction!=4)
				/*判断是否往相反的方向移动*/
	  		snake.direction=3;
      else if(key==RIGHT&&snake.direction!=2)
	     	snake.direction=1;
	  	else if(key==LEFT&&snake.direction!=1)
				snake.direction=2;
	    else if(key==DOWN&&snake.direction!=3)
		   	snake.direction=4;
   }
}
/*主函数*/
void main(void)
{
   int gd=DETECT,gm;
   initgraph(&gd,&gm,"e:\\tc");
   cleardevice();
   /*绘制边框*/
   DrawFence();
   /*玩游戏具体过程*/
   PlayGame();
   getch();
   closegraph();
}
